Field of the Invention
Synchronous Digital Hierarchy (SDH) equipment is the latest generation of equipment that is used to provide high bandwidth communications capabilities for use between telephone exchanges and in other areas where high quality telecomms is required (broadcast video distribution, etc). Embedded within the `traffic` carrying capability of the equipment are data communications channels (DCCs). These channels constitute a datacomms network that uses Open Systems Interconnections (OSI) protocols.
Each piece of equipment constitutes a routeing node in the datacomms network formed by the data channels, and can operate any one of a number of different methods. The present invention is concerned with the interworking of two of the possible routeing methods.
The two routeing methods that will commonly occur in SDH networks are IS--IS (ISO 10589) and quasi-static routeing (where alternate routes may be chosen on link failure). Where this occurs, routeing loops, causing loss of comms, can be caused. The present invention detects the formation of a routeing loop and changes the behaviour of the IS--IS node accordingly.